Pull mem-attribute into release branch

1 files changed, 43 insertions, 3 deletions

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index f45f91d38cab..78d29b79947d 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -660,6 +660,29 @@ efi_memory_descriptor (unsigned long phys_addr)
         return NULL;
 }
 
+static int
+efi_memmap_intersects (unsigned long phys_addr, unsigned long size)
+{
+        void *efi_map_start, *efi_map_end, *p;
+        efi_memory_desc_t *md;
+        u64 efi_desc_size;
+        unsigned long end;
+
+        efi_map_start = __va(ia64_boot_param->efi_memmap);
+        efi_map_end   = efi_map_start + ia64_boot_param->efi_memmap_size;
+        efi_desc_size = ia64_boot_param->efi_memdesc_size;
+
+        end = phys_addr + size;
+
+        for (p = efi_map_start; p < efi_map_end; p += efi_desc_size) {
+                md = p;
+
+                if (md->phys_addr < end && efi_md_end(md) > phys_addr)
+                        return 1;
+        }
+        return 0;
+}
+
 u32
 efi_mem_type (unsigned long phys_addr)
 {
@@ -766,11 +789,28 @@ valid_phys_addr_range (unsigned long phys_addr, unsigned long size)
 int
 valid_mmap_phys_addr_range (unsigned long pfn, unsigned long size)
 {
+        unsigned long phys_addr = pfn << PAGE_SHIFT;
+        u64 attr;
+
+        attr = efi_mem_attribute(phys_addr, size);
+
         /*
-         * MMIO regions are often missing from the EFI memory map.
-         * We must allow mmap of them for programs like X, so we
-         * currently can't do any useful validation.
+         * /dev/mem mmap uses normal user pages, so we don't need the entire
+         * granule, but the entire region we're mapping must support the same
+         * attribute.
          */
+        if (attr & EFI_MEMORY_WB || attr & EFI_MEMORY_UC)
+                return 1;
+
+        /*
+         * Intel firmware doesn't tell us about all the MMIO regions, so
+         * in general we have to allow mmap requests.  But if EFI *does*
+         * tell us about anything inside this region, we should deny it.
+         * The user can always map a smaller region to avoid the overlap.
+         */
+        if (efi_memmap_intersects(phys_addr, size))
+                return 0;
+
         return 1;
 }